This washing machine sized box draws 50kW of power. It wouldn't be able to heat up a cold swimming pool very much, but it would be enough to keep a pool that's already hot at a stable temperature.
let span = 5.days().hours(8).minutes(1);
It feels sort of weird how the first number appears in front, and then all the other ones are function arguments. I suppose if you don't like that you can just write: let span = Span::new().days(5).hours(8).minutes(1);
at the expense of a couple characters, which is not too bad.